AG Experimentelle Nanophysik
We prepare and characterize ultrathin 2D-Materials using methods of surface science. Starting with the prototypical graphene (Nobel Prize in Physics 2010), which consists of a single atomic layer of carbon, many new members of this material class have been discovered in the recent years. Theoretically more than a 100 different materials are possible, however until now only a few have been synthesized.
Our main method for investigation is scanning tunneling microscopy (STM) which allows atomic resolution. We prepare advanced 2D-Materials such as composites of graphene and hexagonal boron nitride or ultrathin semiconductors such as MoS2 under well controlled conditions, and modify those layers specifically, to for example dope them or investigate the interaction with potentially harmful gases from the environment. In the recent years we could show, that electrons can be confined in quantum dots made of graphene, how graphene can be destroyed through bombardement with ions, and how impurity atoms are able to sneak in between (intercalate) the 2D-Materials and the supporting substrate.
8.5.2019 Our paper "Lifting Epitaxial Graphene by Intercalation of Alkali Metals" was published in J. Phys. Chem. C. We have precisely determined the structure of intercalated graphene and find that already a small amount of Lithium is sufficient to fully delaminate graphene from Ir(111). Authors are C. C. Silva, J. Cai, W. Jolie, D. Dombrowski, F. H. Farwick zum Hagen, A. J. Martínez-Galera, C. Schlueter, T.-L. Lee and C. Busse.
29.4.2019 Veronika Blecker joined our group. She will establish evaporation of sulfur from FeS2 for the growth of ultrathin films.
April 2019 Our new VT-STM from Scienta Omicron arrived and got installed.
01.04.2019 We welcome Alice Bremerich as a new group member. In her Bachelorthesis, she will use Auger electron spectroscopy (AES) to characterize surfaces especially 2D materials.
28.3.2019 Our paper "Tomonaga-Luttinger liquid in a box: Electrons confined within MoS2 mirror-twin boundaries" was published in Physical Review X. Here, we observe spin-charge separation in one-dimensional wires. Authors are W. Jolie, C. Murray, P. S. Weiß, J. Hall, F. Portner, N. Atodiresei, A. V. Krasheninnikov, C. Busse, H.-P. Komsa, A. Rosch und T. Michely.
26.3.2019 Our paper "Comprehensive tunneling spectroscopy of quasi-freestanding MoS2 on graphene on Ir(111)" was published in Phys. Rev. B. Here, we use a combination of different modes of scanning tunneling spectroscopy (STS) to reveal the band gap of MoS2 as well as additional critical point energies in the band structure. Authors are C. Murray, W. Jolie, J. A. Fischer, J. Hall, C. van Efferen, N. Ehlen, A. Grüneis, C. Busse, and T. Michely.
15.3.2019 We welcome Paulus Aleksa as a new group member. In his PhD-thesis, he will investigate two-dimensional ferroelectric materials.
12.3.2019 Our paper "Charge density wave phase of VSe2" was published in Phys. Rev. B. In this work we use scanning tunneling spectroscopy (STS) to investigate the change in the electronic structure of VSe2 induced by correlated electrons. Authors are W. Jolie, T. Knispel, N. Ehlen, K. Nikonov, C. Busse, A. Grüneis and T. Michely.
8.1.2019 Our scanning tunneling microscope "TuMA 3" arrived from Münster.
28.11.2018 Our paper "Modifying the geometric and electronic structure of hexagonal boron nitride on Ir(111) by Cs adsorption and intercalation" was published in Phys. Rev. B. Here, we show how the geometric and electronic properties of the ultrathin insulator hBN can me tuned by interacion with the electron donor Cs. Authors are J. Cai, W. Jolie, C. Silva, M. Petrovic, C. Schlueter, T. Michely, M. Kralj, T.-L. Lee, and C. Busse.
6.11.2018 New Member: Thaís Chagas joins the group.
30.10.2018 Joshua Fuhrmann successfully completed his Bachelor thesis: Aufbau eines Rastertunnelmikroskops unter Umgebungsbedingungen
9.10.2018 Dina Wilks successfully completed her Bachelor thesis: Elektrochemischer Transfer von Graphen und hexagonalem Bornitrid
29.8.2018 Our paper "Resonance Raman Spectrum of Doped Epitaxial Graphene at the Lifshitz Transition" was published in Nano Letters. Authors are M. G. Hell, N. Ehlen, B. V. Senkovskiy, E. H. Hasdeo, A. Fedorov, D. Dombrowski, C. Busse, T. Michely, G. di Santo, L. Petaccia, R. Saito, and A. Grüneis. Here, we employ ultra-high vacuum (UHV) Raman spectroscopy in tandem with angle-resolved photoemission
(ARPES) to investigate the doping-dependent Raman spectrum of epitaxial graphene on Ir(111).
20.7.2018 Our paper "Valleys and hills of graphene on Ru(0001)" was published in J. Phys. Chem. C. In this work, we precisely determine the shape of a single layer of graphene using X-ray Standing Waves and find a good match to results from Density Functional Theory. Authors are C. Silva, M. Iannuzzi, D. Duncan,P. Ryan, K. Clarke, J. Küchle, J. Cai, W. Jolie, C. Schlueter, T.-L. Lee, and C: Busse
04.06.2018 New Members: Joshua Fuhrmann and Dina Wilks join the group.
01.05.2018 New Member: Dr. Robin Ohmann joins the group.
16.04.2018 New Member: Dennis Rybakowski joins the group.
08.03.2018 Our paper "Suppression of quasiparticle scattering signals in bilayer graphene due to layer polarization and destructive interference" was published in Phys. Rev. Lett. In this work, we demonstrate that electrons in bilayer graphene can be localized in one of the two layers only.
19.01.2018 Our paper "Molecular beam epitaxy of quasi-freestanding transition metal disulphide monolayers on van der Waals substrates: a growth sstudy" was published in 2D Materials. In this work, we describe a new approach to grow transition metal dichalcogenides on top of graphene and hexagonal boron nitride.